Was replacing the rear springs last weekend and was shocked to see how flimsy the torsion beam is. I am afraid that making it twice stiffer would be sort of like multiplying zero by two: twice as much, yet still nothing.

could you take the measurement and estimate how much resistance 19mm sway bar would create? perhaps you would need to make torsion beam x5 stiffer to accomplish the job.

Just a thought.

Originally Posted by Daox

I call it a solution because its not an actual sway bar. Allow me to explain. The torsion beam suspension we have on our car actually doubles as a sway bar without actually needing a separate sway bar (thus reducing cost). The beam that connects the two rear wheels actually twists when you go over a bump with one wheel and not the other just as a sway bar does. The problem with our beam is it simply isn't stiff enough for most of us. However, if we reinforce it, it acts the same as adding an additional sway bar. That is what my solution is. I am calling them torsion beam clamps.

The torsion beam clamps simply reinforce the torsion beam stiffening it up. Pretty simple right? That is the idea. Keep it simple, keep the cost down. Its basically two pieces of bent steel that form a clamp around the rear torsion beam. The clamp strengthens the beam and helps it resist twisting.

Why hasn't anyone else done this before? I can't find any similar products on the market, so I'm not completely sure. One possibility is it does put additional stress through the torsion beam. Additional stress could lead to failure of components. But, many other aftermarket parts do the same thing such as stiffer springs, chassis braces, etc. Personally, I think that sway bars are more expensive and thus more profitable for companies so they go that route by default.

The benefits of the torsion beam clamps are pretty nice though:
1) They'll be a good amount cheaper than a full blown rear sway bar.
2) You can use as many clamps as you'd like to adjust your desired stiffness. I anticipate that one or two will probably do the job.
3) Installation is ridiculously easy. Simply bolt the two clamp halves together over the rear torsion beam and you're done.

I have done some work with testing things out as much as I can before hand. I ran some computer simulated stress analysis on the beam without any clamps and then with numerous sizes and numbers of clamps on it. This analysis allowed me to reduce the amount of twist in the beam while also optimizing the clamps to not add too much additional stress. I came up with a prototype design based off of that analysis. A single clamp should reduce twisting by about 25%, and two clamps reduce it by about 45%.

The prototypes are in the process of being made as I type this. A member of this forum works at a metal bending shop and I have recently got the blanks made up and into their possession. We will be doing testing as soon as they are made and available. I'll keep you all updated.

This is an amazing idea Daox!!! What type/grade steel are you planning on using? Will you try a couple different types? I would love to buy a couple once available, but I would also like to try making a set on my own, I'll be pulling mine in the shop after work tonight for measurements!